This is a cooperative, deduction-association game with a very unique atmosphere! You have to trust the spirit and listen to your instincts to be able to solve the puzzle. A mysterious murder has taken place in the ancient haunted castle. The culprit did a thorough job and didn't leave even the slightest trace, so the police are powerless. However, the murder cannot go undetected, and it is up to the players to solve the case! One player, the ghost of the victim, gives painted mystical dream cards to his companions. The other players, as experienced mediums, help each other and try to find out which of the possible perpetrators is the real culprit, with which device and where he committed the murder. Mysterium is a creepy mystical board game where nothing is as it seems!